diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -29,6 +29,7 @@
     libc.src.string.strcpy
     libc.src.string.strcspn
     libc.src.string.strlen
+    libc.src.string.strncpy
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -47,6 +47,7 @@
     libc.src.string.strcpy
     libc.src.string.strcspn
     libc.src.string.strlen
+    libc.src.string.strncpy
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
diff --git a/libc/src/string/CMakeLists.txt b/libc/src/string/CMakeLists.txt
--- a/libc/src/string/CMakeLists.txt
+++ b/libc/src/string/CMakeLists.txt
@@ -74,6 +74,14 @@
     strstr.h
 )
 
+add_entrypoint_object(
+  strncpy
+  SRCS
+    strncpy.cpp
+  HDRS
+    strncpy.h
+)
+
 add_entrypoint_object(
   strnlen
   SRCS
diff --git a/libc/src/string/strncpy.h b/libc/src/string/strncpy.h
new file mode 100644
--- /dev/null
+++ b/libc/src/string/strncpy.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for strncpy -----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STRING_STRNCPY_H
+#define LLVM_LIBC_SRC_STRING_STRNCPY_H
+
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+char *strncpy(char *__restrict dest, const char *__restrict src, size_t n);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRNCPY_H
diff --git a/libc/src/string/strncpy.cpp b/libc/src/string/strncpy.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/string/strncpy.cpp
@@ -0,0 +1,29 @@
+//===-- Implementation of strncpy -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/strncpy.h"
+
+#include "src/__support/common.h"
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+// If strlen(src)<n, n-strlen(src) '\0' are appended to dest.
+char *LLVM_LIBC_ENTRYPOINT(strncpy)(char *__restrict dest,
+                                    const char *__restrict src, size_t n) {
+  for (size_t i = 0, j = 0; i < n; ++i) {
+    if (*(src + j) != '\0') {
+      *(dest + i) = *(src + j);
+      ++j;
+    } else
+      *(dest + i) = '\0';
+  }
+  return dest;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -72,6 +72,16 @@
     libc.src.string.strstr
 )
 
+add_libc_unittest(
+  strncpy_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strncpy_test.cpp
+  DEPENDS
+    libc.src.string.strncpy
+)
+
 add_libc_unittest(
   strnlen_test
   SUITE
diff --git a/libc/test/src/string/strncpy_test.cpp b/libc/test/src/string/strncpy_test.cpp
new file mode 100644
--- /dev/null
+++ b/libc/test/src/string/strncpy_test.cpp
@@ -0,0 +1,44 @@
+//===-- Unittests for strncpy----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/strncpy.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(StrNCpyTest, ReturnRightValue) {
+  const char src[] = {'a', 'b', 'c', '\0'};
+  char dest[4];
+
+  char *result = __llvm_libc::strncpy(dest, src, sizeof(src));
+  ASSERT_EQ(dest, result);
+}
+
+TEST(StrNCpyTest, OffsetDest) {
+  const char src[] =      {'a', 'b', '\0'};
+  // Initial values.
+  char eq_dest[7]  = {'z', 'z', 'z', 'z',  'z',  'z', '\0'};
+  char gt_dest[7]  = {'z', 'z', 'z', 'z',  'z',  'z', '\0'};
+  char lt_dest[7]  = {'z', 'z', 'z', 'z',  'z',  'z', '\0'};
+  // Expected results.
+  const char eq[7] = {'z', 'a', 'b', '\0', 'z',  'z', '\0'};
+  const char gt[7] = {'z', 'a', 'b', '\0', '\0', 'z', '\0'};
+  const char lt[7] = {'z', 'a', 'b', 'z',  'z',  'z', '\0'};
+
+  __llvm_libc::strncpy(eq_dest + 1, src, sizeof(src));
+  ASSERT_STREQ(eq_dest, eq);
+  // Following characters are consistent.
+  ASSERT_STREQ(eq_dest + 4, eq + 4);
+
+  __llvm_libc::strncpy(gt_dest + 1, src, sizeof(src) + 1);
+  ASSERT_STREQ(gt_dest, gt);
+  // Following characters are consistent.
+  ASSERT_STREQ(gt_dest + 4, gt + 4);
+  ASSERT_STREQ(gt_dest + 5, gt + 5);
+
+  __llvm_libc::strncpy(lt_dest + 1, src, sizeof(src) - 1);
+  ASSERT_STREQ(lt_dest, lt);
+}